Question

The volume of a rectangular block of stone is 10368 $d{m}^3$ Its dimensions re in the ratio 3 : 2 : 1 If its entre surface is polished at 2 paise per $d{m}^2$ then the total cost will be

• A. Rs 31.50
• B. Rs 31.68
• C. Rs 63
• D. Rs 63.36

Answer 1

The correct option is D Rs 63.36

The dimensions are $3x:2x:x$

The volume is ${6x}^3=10368$.

So, x is ${6x}^3=10368$

$\therefore x=\sqrt[3]{3\frac{10368}{6}}=12$

So, the dimensions are $36cm,24cm$ and $12cm$ respectively.

The surface area is $2(36\times 24+24\times 12+12\times 36)=3168c{m}^2$

Total cost is $3168\times 0.02=Rs.63.36$